Although not related to the aurora, polar stratospheric clouds (also known as nacreous clouds) are a beautiful winter sky phenomenon. They only form when conditions in the stratosphere, a layer of our atmosphere at around 15-25km in altitude, are just right. One very important condition is that the temperature in the stratosphere must be below -78°C.
As can be seen from the images below, current GFS forecasts suggest that the temperature in the stratosphere above the UK will drop to below -80°C over the next couple of days (purple regions).
The nacreous clouds will only be visible when the sun is between 1° and 6° below the horizon, in a period called “nautical twilight”. So your best chances to see the clouds will be just before dawn and just after sunset.
Even with this cold stratosphere over the UK, seeing nacreous clouds isn’t guaranteed. Unsurprisingly, the clouds need moisture to form but, unlike the troposphere were “normal” clouds form, the stratosphere is generally quite dry. If you are lucky enough to spot any nacreous clouds, though, do let us know via the comments below!
2 thoughts on “Possibility for nacreous cloud sightings”
Thank you for the information but we are covered with gray cloud down here in Buckinghamshire
Fingers crossed. Must be a year since the last lot.
Comments are closed.